When an actuator such as a motor is controlled using an IC in which there is a large amount of variation in the command input circuit into which a command from, e.g., a microcomputer is inputted, instances occur in which the output of the actuator does not follow the command as required by the microcomputer.
There is known, as a technique for solving this problem, e.g., in relation to a motor, a speed control device disclosed in the prior art in JP-A 58-99279. In this speed control device, a current minor control loop comprising a current detector and a current adjuster is provided to a speed adjustment loop comprising a speed detector and a speed adjuster, and the actual speed of the motor is controlled so as to reach the target speed.
This Patent Literature also proposes an inexpensive speed control device in which the current value is estimated, whereby the current detector and the current adjuster are removed from the current minor control loop according to the prior art.